With the chemical we may also combine a mechanical stimulus. We can, for example, wipe out the mouth with a sponge soaked in the solution to be experimented with, but always with the same negative result. We may finally give such pieces of sponge, or even smooth stones of considerable size, to the dog to swallow, passing them back behind the anterior pillars of the fauces and allowing them to fall out again, from the upper portion of œsophagus. It may be added that a well-taught dog puts up with all these procedures without the slightest protest. You see that all the manipulations in this case are carried out with bare hands and without instrumental aid. One can easily train a dog to swallow stones which are placed in the anterior part of the buccal cavity. It simply makes a few chewing movements and swallows them down. The dog on which the acid experiment has just been made serves also for the swallowing of the stones. The attendant now places some pebbles in the front part of the mouth, when the animal rolls them round, as if chewing and gnawing them, and then swallows them. The stones fall out, as you see, from the œsophagus, and drop with an audible sound upon the table. This play with the stones has now lasted fifteen or twenty minutes (in the laboratory we have often kept it up for hours), and yet not a drop of gastric juice is to be seen. In order to prove that the dog is perfectly healthy and normal, we lay aside the stones and proceed to our old experiment of sham feeding. As you see, the first drop of gastric juice makes its appearance precisely at the end of five minutes, and after a further five minutes we have collected more than 15 c.c. of the fluid; consequently there can be no doubt that in this dog both gastric glands and nerves are uninjured and function in normal manner. At one time we even had a dog which voluntarily took the stones out of one’s hand and swallowed them; the sagacious creature had seen our object in previous experiments and learned to perform it of its own accord! But in this case also the result was negative. Clearly, therefore, neither chemical nor mechanical stimulation of the buccal mucous membrane is capable of reflexly exciting the nerves of the stomach. Further, it is obvious that the excitation of these nerves in sham feeding is not the result of a stimulation coincidently produced; that is to say, the excitement of the chewing and swallowing centres does not imply simultaneous action of the secretory centre of the gastric glands. In what, then, does this influence consist which is intrinsic to the sham feeding, but which we have not been able to reproduce in our analytical investigation? There is only one thing to think of, namely, the eager desire for food, and the feeling of satisfaction and contentment derived from its enjoyment.